Investigation of Prins reaction for the synthesis of 2, 4-disubstituted tetrahydropyran derivatives and 1, 3-dioxanes using polyaniline supported acid as reusable catalyst

Article abstract of DOI:10.1007/s12039-011-0122-3

The Prins cyclization of homoallyl alcohol with a variety of aldehydes were observed under reflux condition in dichloromethane using both polyaniline supported TsOH (PANI-TsOH) and FeCl₃ (PANI- FeCl₃) as reusable acid catalysts with the formation of 2,4-disubstituted tetrahydropyran ether as single product. In case of 4-, 3- and 2- nitro benzaldehydes, the reaction generated acetal of the aldehyde and homoallylic alcohol as single product. Additionally, both catalysts were investigated for the synthesis of 1, 3-dioxane in dichloromethane under reflux and at ambient temperature Indian Academy of Sciences.

Full text of DOI:10.1007/s12039-011-0122-3

c
J. Chem. Sci. Vol. 123, No. 5, September 2011, pp. 623–630. ꢀ Indian Academy of Sciences.
Investigation of Prins reaction for the synthesis of 2, 4- disubstituted
tetrahydropyran derivatives and 1, 3-dioxanes using polyaniline
supported acid as reusable catalyst
KALYAN JYOTI BORAH and RULI BORAH∗
Chemical Sciences Department, Tezpur University (A Central University), Napaam 784028,
Tezpur-Assam, India
e-mail: ruli@tezu.ernet.in
MS received 19 October 2010; revised 5 January 2011; accepted 16 May 2011
Abstract. The Prins cyclization of homoallyl alcohol with a variety of aldehydes were observed under reflux
condition in dichloromethane using both polyaniline supported TsOH (PANI-TsOH) and FeCl3 (PANI- FeCl3)
as reusable acid catalysts with the formation of 2,4-disubstituted tetrahydropyran ether as single product.
In case of 4-, 3- and 2- nitro benzaldehydes, the reaction generated acetal of the aldehyde and homoallylic
alcohol as single product. Additionally, both catalysts were investigated for the synthesis of 1, 3-dioxane in
dichloromethane under reflux and at ambient temperature.
Keywords. Prins cyclization; heterogeneous catalyst; solid acid; polymer support; acetal.
1. Introduction
In recent years, the efficient use of non-toxic and
more selective supported solid acidic6 catalysts have
received more attention in different areas of organic
synthesis because of their environmental compati-
bility, reusability, high selectivity, simple operation,
cheaper and ease of isolation of the products. As a
result, various solid supported catalysts7 such as MCM-
41, Amberlyst-15 ion exchange resin, zeolite, etc., have
gained importance in the Prins reactions. The potential
use of polymer supported catalysts as heterogeneous
and regenerable catalysts in organic transformation
make reaction methods more convenient, economic
and environmentally benign. Many reactions can be
carried out cleanly, rapidly, and in high yields. The
reaction can be performed under mild conditions,
and product purification is simplified because of the
use of an insoluble solid support. Polymer-supported
catalysts can also be recycled after use. Generally,
the polystyrene-based polymer-bound Lewis acid cat-
alysts show relatively low activity, and the activity
of the catalyst decreases due to insufficient stability
of the aromatic ring of the polymer and slow dif-
fusion of substrate into the network. Moreover, the
actual loading is limited by Lewis acid catalysed cross
linking of chloromethyl groups within the polystyrene-
based resin. The best method to increase the max-
imal loading of the carrier material is obtained by
using low molecular weight functional polymers.8
The acid catalysed Prins reaction of olefins with car-
bonyl compounds is an important reaction for carbon–
carbon bond1 formation which can be used to pre-
pare 1,3-dioxane and tetrahydropyran derivatives via
cyclization reaction. There are several types of Prins
reactions available in the literature. The condensa-
tion of simple olefin–aldehyde leads to the formation
of 1,3-dioxanes2 and coupling of homoallylic alco-
hol with (scheme 1) aldehyde forms tetrahydropyran
derivatives.3 The tetrahydropyran ring is widely dis-
tributed throughout nature e.g., in carbohydrates and
natural products.4 Under the classical condition, the
Prins cyclization requires strong acid as catalyst (e.g.,
HCl, H2SO4 acid) and high temperature reaction con-
dition which often produces a mixture of products.
Specifically, Lewis or Brønsted acids induced polymer-
ization of olefin can severely interfere with desired C–
C bond formation. Therefore, research efforts are being
directed to develop eco-friendly catalytic routes for the
Prins cyclization reaction. Li et al. reported5 the scan-
dium triflate catalysed in situ Prins cyclization reactions
for the synthesis of tetrahydropyran-4-ol and ethers in
chloroform.
∗For correspondence
623

624
Kalyan Jyoti Borah and Ruli Borah
OH
O
O
PANI-acid
OH
+
+
CH2Cl2
reflux
R
H
R
R
O
O
1
2
3
4
R= Aryl
Scheme 1. Prins cyclization of 3-butene-1-ol with aldehyde.
Polyaniline (PANI) is one of the polymers which can be 2. Results and discussion
used as a matrix for catalysis. It is cheap, easy to syn-
In continuation of our research interest in the devel-
thesize, light weight with excellent electrical and chem-
ical properties, number of intrinsic redox states, stabil-
ity and insoluble in a large majority of commonly used
solvents, which are the main advantages of supported
catalysts.9 Many polyaniline supported salts and com-
plexes10 (TsOH, H2SO4, FeCl3, AlCl3 etc.) are exhibit-
ing excellent catalytic activity with less amount of
catalyst in organic synthesis. Polyaniline has acid/base
doping response due to presence of different intrinsic
redox states. In view of this, we studied the catalytic
activity and selectivity of already known polyaniline-
supported TsOH and FeCl3 for the Prins reaction of
homoallylic alcohol with different aldehydes and con-
densation of olefins with paraformaldehyde to produce
the corresponding tetrahydropyran derivatives and 1,
3-dioxanes11 respectively.
opment of environmentally benign syntheses, recently,
we have reported11 silica-supported TsOH, a suitable
acid catalyst for the synthesis of 1, 3-dioxane via Prins
reaction in solvent-free medium. In this context, we
have examined the catalytic activity of TsOH and FeCl3
for the Prins cyclization of 3-butene-1-ol with p-chloro
benzaldehyde in organic solvents as well as in ionic liq-
uids at different temperatures to form 2, 4-disubstituted
tetrahydropyran derivatives. The results are shown in
table 1.
But in both cases, less selectivity were observed
for the formation of corresponding products. As such
no reported work has been found regarding use of
polyaniline-supported acid as suitable catalyst to the
Prins cyclization. Here we have improved the cataly-
Table 1. TsOH and FeCl3 catalysed Prins cyclization of 3-butene-1-ol with 4-chlorobenzaldehyde
in different solvents.
Entry
Solvent
Catalyst
Temp (◦C)
Time(h)
Products (Yield %)a
3
4
1
2
3
4
5
6
7
CH2Cl2
CH2Cl2
TsOH
FeCl3
TsOH
FeCl3
TsOH
FeCl3
TsOH
FeCl3
TsOH
FeCl3
TsOH
FeCl3
TsOH
FeCl3
r.t.
40
65
70
r.t.
70
r.t.
5
8
38
35
40
34
42
36
23
25
18
10
22
17
15
10
42
38
45
37
40
39
15
17
20
15
25
21
35
30
CHCl3
7
EtOH
6
[bmim]BF4
[bmim]BF4
[bmim]PF6
20
12
12
aAll products were characterized by 1HNMR and also their TLC comparison with authentic sample
prepared by reported method

Investigation of Prins reaction for the synthesis of tetrahydropyran and dioxane derivatives
625
tic activity and selectivity of the Prins cyclization zaldehydes (table 2, entries 10,11,12) with 3-buten-1-
(scheme 1) by refluxing the aromatic aldehydes ol generated acetal 7 as single product. The presence of
1(2 mmol), 3-butene-1-ol 2 (4 mmol) and catalytic nitro group increases the electrophilic character of car-
amount of polyaniline-supported TsOH(0.25 mmol) or bonyl carbon of aldehyde which shows more tendency
FeCl3 (0.25 mmol) together in dichloromethane. These to react with strong nucleophile like alcoholic group of
two catalysts generated 2, 4-disubstituted tetrahydropy- 3-butene-1-ol to form 7 as the only product. Other aro-
ran ether 4 as single product from various aromatic matic aldehydes prefer to form 4 via Prins cyclization
aldehydes (table 2, entry 4–8).
due to less electrophilic nature of carbonyl carbon as
Treatment of equal amount of 4-chlorobenzaldehyde compared to nitro benzaldehydes.
(1 mmol) and 3-buten-1-ol (1 mmol) also resulted
The stereochemistry of 2, 4-disubstituted tetrahy-
incomplete of reaction with the formation of 2, 4- dropyran ether 4 was reported5 as cis- based on the cou-
disubstituted tetrahydropyran ether 4 (table 2, entry 9) pling constants of the protons at the H-2 and H-4. The
as single product. The selectivity of TsOH and FeCl3 presence of an axial–axial coupling was identified from
catalysts were found to be better on the surface of poly- the coupling constant value of approximately 11 Hz for
mer support for the Prins cyclization as compared to such protons.
non-supported catalysts (table 1). The reusability of
A DEPT study of the three new compounds(7d,7e,7f)
the two catalysts was also observed four times without revealed that (figure 1) each DEPT -135 spectrum
loss of their catalytic activity and selectivity in case of shows three negative signals for six -CH2- groups and
reaction between 4-chlorobenzaldehyde and 3-butene1- different positive signals for seven - CH- groups while
ol to form the corresponding tetrahydropyran product no peaks for two quaternary carbons. In addition, the
(table 3). A possible mechanism for this Prins cycliza- COSY spectrum of compound 7d reveals that the sig-
tion is shown in scheme 2. Interestingly, the reaction of nal at δ 2.28 (q, J = 6.7 Hz C-2) shows large cross
electron deficient aldehydes like o-, m- and p- nitroben- peaks with the signals at δ 3.47–3.49 (C-1) and δ 5.73–
Table 2. PANI-TsOH and PANI- FeCl3 catalysed Prins cyclization of 3-butene-1-ol with various aldehydes in
dichloromethane under reflux condition.
Entry
Aldehyde
Catalyst
Time(h)
Product
3
Yield(%)
Product
4/7
Yield (%)a,c
4/7
1
2
3
4
C6H5
C6H5
C6H5
C6H5
TsOH
FeCl3
8
6
22
8
9
6
6.5
5
6
3a
3a
-
-
-
40
34
-
-
-
4a
4a
4a
4a
45
37
55b
55
50
45
42
76
72
63
57
60
55
40d
38
85
82
84
83
86
80
PANI-TsOH
PANI-TsOH
PANI- FeCl3
PANI-TsOH
PANI- FeCl3
PANI-TsOH
PANI- FeCl3
PANI-TsOH
PANI- FeCl3
PANI-TsOH
PANI- FeCl3
PANI-TsOH
PANI- FeCl3
PANI-TsOH
PANI- FeCl3
PANI-TsOH
PANI- FeCl3
PANI-TsOH
PANI- FeCl3
5
4-Me C6H4
4-Cl C6H4
-
-
4b
4c
4d
4e
4c
7d
7e
7f
6
-
-
-
-
-
-
-
-
-
-
-
-
-
-
7
2-Cl C6H4
8
8
3-Br C6H4
8
9
4-Cl C6H4
7
8
4
10
11
12
4–NO2− C6H4
3–NO2− C6H4
2-NO2− C6H4
4.5
4
6
aIsolated yields. bRoom temperature reaction. cAll products were characterized by FT-IR, 1HNMR, CHN analyzer
and also their comparison5 with authentic sample. dThis reactions was carried out in 1 mmol scale with molar ratio
1: 1:0.12 of aldehyde/3-butene-1-ol /catalyst

626
Kalyan Jyoti Borah and Ruli Borah
Table 3. Recycling of PANI-TsOH and PANI- FeCl3
catalysed Prins cyclization of 3-butene-1-ol with 4-
chlorobenzaldehydes in dichloromethane under reflux
condition.
Entry
Catalyst
Time(h)
Number
Product 4c
of cycles Yield (%)a
1
PANI-TsOH
5
1
2
3
4
1
2
3
4
76
74
75
74
72
72
70
71
2
PANI- FeCl3
6
aThis reaction was carried out in 1 mmol scale with molar
ratio 1: 2 :0.12 of aldehyde/3-butene-1-ol /catalyst
Figure 1. DEPT-135 spectra of 7d, 7e and 7f.
5.75 (C-3) of 3-butenoxy groups of acetal. The other
two compounds (7e, 7f) also showed similar correla-
tions pattern among the three nearby protons at C-1, C-2
and C-2 of 3-butenoxy group.
Subsequently, we examined the polyaniline-supported
PTSA/FeCl3 catalysed Prins reactions of paraformalde-
hyde and various alkenes in dichloromethane at differ-
ent temperatures.
improved results with 1-octene under reflux condition
in dichloromethane (table 4, entry 16). Again, the use
of formalin was found to be efficient in certain cases
under reflux condition within short time (table 4, entries
8, 17).
3. Experimental
These results (table 4, entries 2,7,10,13,15) revealed
that both catalysts decrease their reactivity in presence
of polymer support for the synthesis of 1,3-dioxane 9 in
3.1 General information
dichloromethane with respect to TsOH/ FeCl3 catalysts All chemicals are commercially available and were
at room temperature. Both supported catalysts showed used without further purification. The products were
OH
OH
H
R
R
OH
H+
HO
5
2
+OH2
O
R
O
O
H
R
1
R
O
7
O
O
OH
-H2O
2
R
+
-
H
4
R
O
6
R
O
Scheme 2. The Plausible mechanism for Prins cyclization of 3-butene-1-ol
with various aldehydes catalysed by PANI-TsOH and PANI- FeCl3.

Investigation of Prins reaction for the synthesis of tetrahydropyran and dioxane derivatives
627
Table 4. Synthesis of 1,3-dioxane using PANI- TsOH and PANI- FeCl3 in
dichloromethane.
(CH2O)n
R1
R2
H
CH2Cl2
R1
R2
O
O
Cat.
H
H
9
8
aIsolated yields. All products were characterized by FT-IR, 1HNMR, CHN analyzer and
also their comparison with reported data12
identified by comparison of their FT-IR, 1HNMR spec-
troscopic data and CHN analyzer data with those of
authentic compounds (prepared by known method)
and literature reported data.5,12 The polyaniline sup-
ported catalysts were prepared using already reported
method.10
(i) Preparation of polyaniline salt. In a 500 ml
round bottom flask, 15 ml of sulfuric acid was
slowly added to a solution of 350 ml of water
with stirring. To the stirring solution, 5 ml of
aniline was added and the temperature was
maintained at 5–10◦C. The above solution was
allowed to continue for stirring for 4 h in pres-
ence of 130 ml aqueous solution of sodium
persulfate (12 gm) at 5–10◦C. The precipitated
polyaniline powder was filtered and washed
with 2 L distilled water followed by 200 ml ace-
tone. The polyaniline salt powder was dried at
100◦C till a constant weight.
3.2 Experimental procedure
3.2a Methods for the preparation of polyaniline sup-
ported acid catalysts: The synthesis of polyaniline
supported TsOH and FeCl3 catalysts involved in three
steps. The polyaniline salt and base were prepared by
aqueous polymerization pathways.
(ii) Synthesis of polyaniline base. In this step,
polyaniline salt powder (3.5 gm) was taken in a

628
Kalyan Jyoti Borah and Ruli Borah
500 ml round bottom flask and stirred in 350 ml acetate–n-hexane (1:9) as eluent to find pure product
aqueous sodium hydroxide solution (1.0 M) for 1,3-dioxane.
8 h at ambient temperature. Polyaniline base
was precipitated, washed with water and ace-
3.5 Spectral data of selected compounds
tone. The base was dried at 100◦C till a constant
weight.
3.5a cis-2-Phenyl-4-(3-butenoxy)-tetrahydropyran (4a):
Light yellow liquid, 1HNMR (400 MHz, CDCl3)δ 7.42–
7.23(m,5H), 5.84(m,1H), 5.13-5.08(m,2H), 4.31(dd,
J = 11.3,2.4 Hz, 1H),4.22 (ddd, J = 11.5,4.2, 1.3 Hz,
1H) 3.65(m,1H), 3.60(t, J = 6.7 Hz, 2H), 3.57(m,1H),
2.39(q, J = 6.7 Hz, 2H), 2.23(m, 1H), 2.00(m, 1H)
1.63(m,1H),1.55(m,1H); IR (KBr) cm−1 1493, 1447,
1350, 1327, 1309, 1165, 1145,1098, 1082,1037, 1021,
986, 954, 907; 13C NMR (CDCl3, 400 MHz, ppm):
δ = 142.1, 135.2, 128.3,127.7, 126.0, 116.2, 78.2, 75.3,
67.1, 66.0, 40.2, 34.8, 32.5; GC/MS: m/z (%base peak)
(M++1,),233,232, 177, 161, 160,159,131,117,105, 91,
77, 71,55(100) CHN Anal. Cal C15H20O2; C 77.55, H
8.68; found C 77. 60, H 8.50
(iii) Redoped polyaniline salt. Initially, 50 ml of
1.0 M two standard solution of PTSA and FeCl3
in acetone was prepared separately. Polyani-
line base (0.5 gm) was added to each of the
above solution and kept under constant stirring
at ambient temperature for 4 h. Solid was fil-
tered, washed with acetone and the solid was
dried at 100◦C till a constant weight. Amount
of acid group present in the polymeric chain
was calculated based on the weight of redoped
polyaniline salt obtained and the weight of poly
aniline base used. Amount of dopant present in
PANI-TsOH and PANI- FeCl3 were found to be
42.5% and 29.5% respectively.
3.5b cis-2-(4-Methylphenyl)-4-(3-butenoxy)-tetrahy-
dropyran (4b): Light yellow liquid,1HNMR (400 MHz,
CDCl3) δ 7.30(d, J = 8.4 Hz, 2H), 7.20(d, J = 8.4 Hz,
2H), 5.87(m,1H), 5.14–5.06(m,2H), 4.32(dd, J = 11.2,
2.0 Hz, 1H),4.20 (ddd, J = 11.6, 4.5, 1.7 Hz, 1H),
3.64(m,1H), 3.57(t, J = 6.9 Hz, 2H), 3.56(m,1H),
2.38(q, J = 6.9 Hz, 2H), 2.35(s, 3H), 2.23(m, 1H),
2.03(m,1H), 1.64(m,1H), 1.56(m,1H); IR (KBr) cm−1
1638, 1540, 1436, 1363, 1309, 1245, 1164, 1144,
1108, 1082, 1022, 993, 959;13C NMR(CDCl3,
400 MHz,ppm):δ = 139.3, 137.4, 135.3, 129.0, 126.1,
116.5, 78.2, 75.5, 67.0, 66.4, 40.2, 34.5, 32.8, 21.2;
GC/MSm/z(%base peak)247(M++1), 246, 245, 231,
205, 175, 174 (100), 173, 159, 146, 145, 129, 121,
120, 119, 118, 105, 93, 87, 77, 71, 55; CHN Anal. Cal
C16 H22O2; C 78.01, H 9.00; found C 78.20, H 9.01.
3.3 Method for preparation of tetrahydropyran
derivatives
A mixture of 3-butene-1-ol (4 mmol), 4-chloroben-
zaldehyde (2 mmol) and PANI-TsOH (0.25 mmol) or
PANI-FeCl3 (0.25 mmol) in dichloromethane (10 ml)
was refluxed for the specified reaction period. On com-
pletion, as indicated by TLC, the catalyst was fil-
tered and washed with dichloromethane (2 ×15 ml).
The combined organic layers were washed with water,
sodium bicarbonate solution, dried over anhydrous
sodium sulfate and concentrated in vacuum. The result-
ing reaction mass was purified by column chromatog-
raphy on silica gel (Merck,60–120 mesh) using hexane
and ethyl acetate as eluent to afford 2,4 disubstituted
tetrahydropyran ether as pure product.
3.5c cis-2-(4-Chlorophenyl)-4-(3-butenoxy)-tetrahy-
dropyran (4c): Light yellow liquid,1HNMR (400 MHz,
CDCl3)δ 7.29(d, J = 8.3 Hz, 2H), 7.25(d, J = 8.3 Hz,
2H), 5.84(m,1H), 5.13–5.04(m,2H), 4.31(dd, J = 11.3,
2.0 Hz, 1H),4.19 (ddd, J = 11.3, 4.8, 1.7 Hz, 1H),
3.61(m,1H), 3.57(t, J= 6.7 Hz, 2H), 3.55(m,1H),
2.34(q, J = 6.7 Hz, 2H), 2.22(m,1H), 2.05(m, 1H),
1.58(m,1H), 1.46(m,1H); IR (KBr) cm−1 1639, 1492,
1436, 1357, 1309, 1245, 1156, 1108, 1077, 1012,
993;13C NMR (CDCl3, 400 MHz, ppm): δ = 140.6,
135.3, 133.1, 128.4, 127.0, 116.2, 77.6, 75.1, 67.0,
66.2, 40.1, 34.3, 32.6 GC/MS : m/z(%base peak)
269(M++1), 268, 266, 232, 195, 194,193(100), 165,
140, 139, 128, 125, 111,103, 98, 77, 71, 56, 55, 43,41
3.4 Method for the preparation of 1, 3-dioxane
A mixture of styrene (3 mmol) and paraformaldehyde
(3 mmol) and PANI-TsOH (0.25 mmol) or PANI-FeCl3
(0.25 mmol) was stirred (refluxed) in dichloromethane
at the specified reaction temperature. After comple-
tion of the reaction as indicated by TLC, the reac-
tion mixture was filtered, diluted the filtrate with water
and extracted with dichloromethane (2 × 10 ml). The
combined organic layers were dried over anhydrous
sodium sulfate and distilled under reduced pressure in a
rotary evaporator. The crude reaction mixture was fur-
ther purified by column chromatography using ethyl

Investigation of Prins reaction for the synthesis of tetrahydropyran and dioxane derivatives
629
CHN Anal. Cal C15 H19O2 Cl; C 67.54, H 7.18; found 64.5, 34.3; GC/MS: m/z (%base peak) (M+)277, 222,
C 67.45, H 7.16
206, 205, 176, 153, 152, 136, 121, 105, 77, 57, 55(100);
CHN Anal. Cal C15H19O4 N; C 64.70, H 6.86, N 5.07;
found C 64.90, H 6.85, N 5.05
3.5d cis-2-(2-Chlorophenyl)-4-(3-butenoxy)-tetrahy-
dropyran (4d): Light yellow liquid,1HNMR (400 MHz,
CDCl3)δ 7.52 (dd, J = 7.7, 1.9 Hz, 1H), 7.32–7.15(m,
3H), 5.85(m,1H), 5.13–5.04(m,2H), 4.68(dd, J = 11.5,
2.0 Hz, 1H),4.18 (ddd, J = 11.5, 4.6, 1.4 Hz, 1H),
3.67(m,1H), 3.59(m, 1H), 3.52(t, J = 6.9 Hz, 2H),
3.5h Di-(3-butenoxy) methyl -2nitrobenzaldehyde (7f,
1
liquid, new compound): Colourless liquid, HNMR
(400 MHz, CDCl3)δ 7.81–7.83 (m, 2H), 7.61 (t, J =
7.6 Hz, 1H), 7.43(t, J = 7.6 Hz,1H), 6.09 (s,1H), 5.79–
5.86(m,2H), 5.07–5.13(m,4H), 3.68–3.70(m,2H), 3.59-
3.61(m,2H), 2.39(q,J =6.7 Hz,4H);IR(KBr)cm−1 2925,
1702, 1530, 1441, 1351, 1270, 1193, 1110, 1062,
917;13C NMR(CDCl3, 400 MHz, ppm) : δ = 148.9,
134.8, 133.1, 132.4, 129.2, 128.1, 124.1, 116.7, 98.3,
66.9, 34.0; GC/MS: m/z(%base peak) (M+)277,222,
206, 205, 176, 152, 136, 121, 105, 104, 77, 56, 55(100);
CHN Anal. Cal C15H19O4 N; C 65.00, H 6.89, N 5.08;
found C 64.90, H 6.85, N 5.05
2.37(m, 1H), 2.31(q, J
=
6.9 Hz, 2H), 2.00(m,
1H), 1.62(m,1H), 1.28(m,1H); IR (KBr) cm−1 1637,
1566,1472, 1362, 1247, 1203, 1144,1108, 1082, 1052,
988; CHN Anal. Cal C15 H19O2 Cl; C 67.54, H 7.18;
found C 67.57, H 7.22
3.5e cis-2-(3-Bromophenyl)-4-(3-butenoxy)-tetrahy-
dropyran (4e): Light yellow liquid,1HNMR (400 MHz,
CDCl3)δ 7.50(s,1H), 7.36 (d, J = 7.6 Hz, 1H), 7.23(d,
J = 7.6 Hz, 1H), 7.16 (t, J = 7.6 Hz, 1H), 5.84(m,1H),
5.10-5.04(m,2H), 4.28(dd, J = 11.5, 2.0 Hz, 1H),4.18
(ddd, J = 11.5, 4.8, 1.6 Hz, 1H), 3.58(m,1H), 3.53(t,
J = 6.8 Hz, 2H), 3.48(m,1H), 2.30(q, J = 6.8 Hz, 2H),
2.20(m, 1H), 2.02(m,1H), 1.62(m,1H), 1.45(m,1H); IR
(KBr) cm−1 1636, 1592, 1560, 1467, 1363, 1247, 1205,
1166, 1144, 1107, 1082, 1022, 992; CHN Anal. Cal
C15 H19O2Br; C 57.89, H 6.15; found C 57.92, H 6.17.
4. Conclusion
This article describes the comparative studies of
polyaniline-supported catalyst TsOH and FeCl3 for the
Prins cyclization of homoallylic alcohols with differ-
ent aromatic aldehyde to afford the corresponding 2,4-
disubstituted tetrahydropyran derivatives and conden-
sation of olefins with paraformaldehyde to produce
1,3-dioxanes in organic solvents
3.5f Di-(3-butenoxy)methyl -4-nitrobenzaldehyde (7d,
new compound): Colourless liquid, 1HNMR (400 MHz,
CDCl3)δ 8.09(d, J = 8.7 Hz, 2H), 7.58 (d, J =
8.7 Hz,2H), 5.75–5.73(m,2H), 5.52 (s, 1H), 4.97–5.04
(m, 4H), 3.47–3.49(m,4H), 2.28 (q, J = 6.7 Hz, 4H);
IR(KBr)cm−1 2927, 2877, 1641, 1605, 1524, 1343,
1203, 1103, 1055, 915, 852, 717, 634, 546;13C NMR
(CDCl3, 400 MHz, ppm): δ = 147.9, 146.0, 145.7,
135.0, 127.8, 123.4, 116.7, 100.0, 64.8, 34.3; GC/MS:
m/z (%base peak) (M+) 277, 222, 206, 176, 152, 136,
121, 105, 77, 76, 71, 56, 55(100); CHN Anal. Cal
C15H19O4 N; C 64.72, H 6.88, N 5.07; found C 64.90,
H 6.85, N 5.05
Acknowledgements
The authors are thankful to Council of Scientific and
Industrial Research (CSIR), New Delhi, India for grant-
ing a Research Project No. 32-209/2006(SR) to RB.
References
1. (a) Adams D R and Bhatnagar S P 1977 Synthesis 10
661; (b) Arundale E and Mikeska L A 1952 Chem. Rev.
51 505; (c) Overman L E and Pennington L D 2003 J.
Org. Chem. 68 7143; (d) Zhang W-C and Li C-J 2000
Tetrahedron 56 2403
2. (a) Delmas M 1980 Synthesis 11 871; (b) Delmas M and
Gaset A 1981 Tetra. Lett. 22 723; (c) Bach T and Lobel J
2002 Synthesis 17 2521; (d) Li G, Gu Y, Ding Y, Zhang
H, Wang J, Gao Q , Yan L and Suo S 2004 J. Mol. Catal.
A: Chem. 218 147; (e) Sreedhar B, Swapna V, Sridhar C,
Saileela D and Sunitha A 2005 Syn. Commun. 35 1177;
(f) Gu Y, Ogawa C and Kobayashi S 2006 Chem. Lett.
35 1176; (g) Gu Y, Karam A, Jerome F and Barrault J
2007 Org. Lett. 9 3145; (h) Reddy S S, Raju B D, Kumar
V S, Padmasri A H, Narayanan S and Rao K S R 2007
Catal. Commun. 8 261; (i) Yadav J S, Reddy B V S,
Gopal A V H, Kumar G G K S, Madavi C and Kunwar A
3.5g Di-(3-butenoxy) methyl -3 nitrobenzaldehyde (7e,
new compound): Colourless liquid 1HNMR (400 MHz,
CDCl3) δ 8.33(s, 1H), 8.15(d, J = 7.7 Hz, 1H),
7.80(d, J = 7.7 Hz, 1H), 7.53 (t, J = 7.7 Hz,1H),
5.81–5.82(m,2H), 5.60(s, 1H), 5.07-5.12(m, 4H), 3.55-
3.56(m,4H), 2.38(q,J =6.7 Hz,4H);IR(KBr)cm−12921,
1704, 1642, 1530, 1473, 1436, 1350, 1206, 1111, 1051,
990, 916;13CNMR(CDCl3, 400 MHz,ppm): δ = 147.9,
140.6, 134.6, 132.6, 128.9, 123.0, 121.7, 116.5, 99.6,

630
Kalyan Jyoti Borah and Ruli Borah
C 2008 Tetra. Lett. 49 4420; (j) Wang W, Shao L, Cheng
W, Yang J and He M 2007 Catal. Commun. 9 337
Chem. 210 99; (c) Aramendia M A, Borau V, Jimenez
C, Marinas J M, Romero F J and Urbano F J 2001 Catal.
Lett. 73 203
3. (a) Zhang W C, Viswanathan G S and Li C J 1999 Chem.
Commun. 3 291; (b) Keh C C K, Namboodiri V V, Varma
R S and Li C-J 2002 Tetra. Lett. 43 4993; (c) Keh C C K
and Li C-J 2003 Green Chem. 5 80; (d) Yadav J S, Subba
Reddy B V, Narayana Kumar G G K S and Aravind S
2008 Synthesis 3 395
4. (a) Nicolaou K C and Sorensen E J 1996 Classics
in Total Synthesis, VCH, Weinheim; (b) Molinski T F
1996 Tetra. Lett. 37 7879; Fusetani N, Shimoda K and
Matsunaga S 1993 J. Am. Chem. Soc. 115 3977
8. Barth M and Rademann J 2004 J. Comb. Chem. 6 340
9. (a) Blaz E, Pielichowski J 2006 Molecules 11 115; (b)
Lee B, Ko N H, Ahn B S, Cheong M, Kim H S and Lee
J S 2007 Bull. Korean. Chem. Soc. 28 2025
10. (a) Gangadasu B, Palaniappan S, Amarnath C A and Rao
VJ 2006 J. Appl. Poly. Sci. 102 1741; (b) Palaniappan
S, John A, Amarnath C A and Jayathirtha R V 2004 J.
Mol. Catal. A 218 47; (c) Palaniappan S, Saravanan C,
Amarnath C A and Jayathirtha R V 2004 Catal. Lett. 97
77
5. (a) Yadav J S, Reddy B V S, Sekhar K C and Gunasekar
D 2001 Synthesis 6 885; (b) Zhang W-C and Li C-J 2000 11. Borah K J, Phukan M and Borah R 2008 Synth.
Tetrahedron 56 2403 Commun. 38 3082
6. (a) Chari M A and Syamasundar K 2005 Catal. Com- 12. (a) Tateiwa J, Hashimoto K, Yamauchi T and Uemura S
mun. 6 67; (b) Kobayashi S and Nagayama S 1996 J.
Org. Chem. 61 2256
7. (a) Villa de P A L, Alarcon E and Montes de C C 2002
Chem. Commun. 22 2654; (b) Yadav J S, Reddy B V
S, Reddy M S and Niranjan N 2004 J. Mol. Catal. A :
1996 Bull. Chem. Soc. Jpn. 69 2361; (b) Chandrasekhar
S and Reddy B V S 1998 Synlett. 8 851; (c) Yadav J S,
Reddy B V S, and Bhaidhya G 2003 Green Chemistry
5 264; (d) Du Y and Tian F 2007 Catal. Commun. 8
2012